Objective
The objectives of this project are the following:
To describe as precisely as possible, by means of high performance spectroscopic methods, the physico-chemical characteristics of particles emitted by overheated nuclear fuel as a consequence of a reactor accident.
These characteristics closely depend on the chemical history of the particles:
during the emission process from the fuel;
during the transient phase in the plume emitted by the core, at intermediate temperatures and under oxidizing or reducing conditions.
These conditions will be realised in a laboratory simulator which reproduces as closely as possible the physical and chemical conditions likely to exist in the fuel and in the plume of a damaged reactor.
The particles generated by this simulator will be submitted to high-performance spectroscopic methods in order to define the characteristics of the radionuclides (RN) they contain.
The solubility of these RN will be assayed in relation with the results from the analyses.
Comparisons will be made with the observations already performed on particles from Chernobyl in Russian laboratories.
The expected results are the following:
Although quite a lot of information has been gathered about fuel particles collected around Chernobyl, the mechanisms of their formation is far from being fully understood, all the more since the characteristics of the emission significantly varied during the 9 days of the core fire. The present project intends to correlate the properties of fuel particles with precisely defined emission parameters.
Collaboration between specialized laboratories allows to combine different high performance spectroscopic methods. This will provide an outstanding amount of information about the chemical nature of the particles.
There will be a strong connection between the physico-chemical characteristics of the particles and the rate of mobilization (solubilisation) of the RN they contain. In particular, thanks to the generation of particles in the laboratory, it is possible to better define the amount of radioactive material which is likely to be rapidly mobilized in the environment (RN condensed onto the surface of the aerosols). This has been almost impossible during the accident at Chernobyl. The fraction of rapidly 'mobilizable' radioactive material is of prime importance in the remediation procedures to be decided just after an accident. Only a good knowledge of the physico-chemical processes leading to the more or less intensive integration of the RN into the particles can help in that matter
It has to be emphasized that this study also addresses particles of very low diameter which are practically impossible to isolate and to study as such once deposited onto soils. In the case of the Chernobyl accident, these particles have been simply considered as condensed matter. In fact, being made of oxides of very low solubility, they are also able to delay significantly the mobilization of RN as has already been demonstrated with particles generated in the laboratory. This observation could probably explain the unprecedented observation, made at Chernobyl, that a fraction of radioactive strontium was being mobilized only a few years after the accident (1994-1995) even when it is recognized that, as a cation, Sr is very mobile in soils.
An important issue of the project will be the translation and publication in English of all the analyses performed in St Petersburg about the microstructure of 150 fuel particles which have been analyzed so far.
Topic(s)
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Data not availableFunding Scheme
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1348 Louvain-la-Neuve
Belgium